In a fuel injection device of the type to which the present invention pertains the fuel that is ejected via the injection opening of the injection nozzle is mixed with a partial air stream from the air chamber and issues from the outlet opening as a fuel-air mixture, either into the induction passage or directly into the working zone of the engine, according to the position of the injection nozzle. In this way it is possible to achieve effective turbulence in the air flow and atomization of the fuel and thus a satisfactory mixture. The air chamber or its communication with the atmosphere, however, may restrict the amount of air which flows through the air chamber to only a fraction of the amount of air required for idle running, the further air requirement being supplied via an idle running adjustment device of the usual type. This means that the proportion of air flowing through the air chamber of the fuel injection device becomes smaller as the load on the internal combustion engine increases, and thus the proportion of the mixture satisfactorily generated by the air chamber of the nozzle also becomes smaller. Since this mixture preparation is limited to such a small operating range, and also because the ejected fuel, in the upper loading range and on full load, may become deposited on the walls inside the air chamber, on account of the usual fall in depression in the induction passage and thus in the region of the injection nozzle, the result may be an increase in fuel consumption and deterioration of the content of the exhaust gas.